The 'clean' target now kills the openssl server if .server.pid is found.

Makefile

@@ -5,6 +5,7 @@ install:
 	chmod 755 /usr/local/bin/ssl-ca
 
 clean:
+	[ -f .server.pid ] && kill "$$(cat .server.pid)"
 	rm -rf openssl.cnf certs keys CA.key CA.crt CA.p12 CA.srl .server.pid
 
 test: clean